Question

Resolva as equações do 2° grau usando a fórmula de bháskara.

a) x² - 18x + 72 = 0
b) x² + 10x + 9 = 0​

Answer 1

Resposta:

a) S = {12, 6}

b) S = {-1, -9}

Explicação passo a passo:

a)

$\triangle=b^2-4ac\\\triangle=(-18)^2-4*1*72\\\triangle=324-288\\\triangle=36$

$\displaystyle x=\frac{-b\pm\sqrt{\triangle}}{2a}$

$\displaystyle x=\frac{-(-18)\pm\sqrt{36}}{2*1}$

$\displaystyle x=\frac{18\pm6}{2}$

$\displaystyle x1=\frac{18+6}{2}$

$\displaystyle x2=\frac{18-6}{2}$

$\displaystyle x1 = 12\\x2 = 6$

b)

$a = 1, b = 10, c = 9\\\triangle=b^2-4ac\\\triangle=10^2-4*1*9\\\triangle=100-36\\\triangle=64$

$\displaystyle x=\frac{-b\pm\sqrt{\triangle}}{2a}$

$\displaystyle x=\frac{-10\pm\sqrt{64}}{2*1}$

$\displaystyle x=\frac{-10\pm8}{2}$

$\displaystyle x1=\frac{-10+8}{2}$

$\displaystyle x2=\frac{-10-8}{2}$

$\displaystyle x1=-1\\x2 =-9$